Water Supply Outlook for Alberta

June 2004

Mountain Snowpack

Remaining snow accumulations in the mountains as of June 1, 2004 are generally below-average to average in the Oldman, Bow, Red Deer, and North Saskatchewan River basins, and below-average to much-below-average in the Athabasca and Smoky River basins for this time of the year (Table 1). Although snowmelt during May was minimal, as of early June mountain snowmelt is well underway in the Bow, Red Deer, and North Saskatchewan River basins. As a result, water levels in mountain-fed streams have recently risen to near-average or better levels. In the Oldman and Milk River basins, snowmelt peaked about a month ahead of usual, but there is still snowmelt contributing to streamflows in those basins. Typically the peak snowmelt runoff from the mountain areas occurs in late May or June. The mountain snowpack is an important source of water supply to reservoirs in the province.

Three snow courses were measured at the end of May in the Oldman River basin (Table 2). This remaining snowpack is below-average to average for this time of year, with values ranging from 5 to 94% of average.

Thirteen snow courses were taken at the end of May in the Bow River basin, with twelve values ranging from 43 to 121% of average and one lower elevation location recording sero snow left (Table 3). Snowpack measurements are generally below-average to average for this time of year. June 1 snowpack is generally lower than last year, much lower than those recorded in 2002, and much higher than the near record lows observed on June 1 of 2001.

Four snow courses were measured in the Red Deer River basin on June 1, with values ranging from 0 to 89% of average, which is below-average to average for this time of year. The snowpack is lower than at this time in either 2003 or 2002. Snow course data is available in Table 4.

At twelve snow course sites, real-time snow accumulation can be monitored using snow pillows. Snow pillows can be viewed by choosing any mountainous southern basin, and snow data, in the two drop down menus at:


Snow water equivalent values on the snow pillow may or may not match the snow course value at a particular location. While snow pillow data is very valuable information, the quantity of snow on the pillow is only representative of the accumulation at that specific spot. A snow course survey is measured at numerous spots and provides a more representative value of snow in the area. In some locations, there can be considerable difference between the snow pillow and snow course values. Factors such as wind and exposure of the site can cause the snow pillow values to be significantly different from the snow course survey. The snow pillow graphs on our website show the daily average snow water equivalent. The monthly snow survey is the average of all measurements conducted within five days of the end of the month. Also, where snow pillow and snow course measurements are available for the same site, snow pillow records tend to be much shorter (10-15 years) in length compared to the snow course sites. As a result, the difference in the average value between the snow pillow and the snow course can be attributed to snow water equivalent being derived two different ways (physically measured compared to an instrument reading), site location and length of data record. In some cases, the values can deviate by 10-20%. Therefore, while snow pillows are excellent for analyzing trends and for monitoring accumulation between snow surveys, snow course values should always be used when considering the quantity of snow at a particular location as they best represent that area.

Click here to see a map of snow course locations

For technical enquires about this web page please contact Alberta Environment - Environmental Management Water Management Operations Branch at AENV-WebWS@gov.ab.ca